Could I be pregnant?

So I had sex on the 5th of this month, I have the nexaplanon but I don’t bleed. So since I don’t have a period I don’t know if I could be pregnant or not.

These past two weeks I’ve been nauseous everyday, usually lasts for 20 minutes but I never throw up. My heart tends to race when this happens as well.

I’ve been getting lightheaded these past two days, it has happened twice today.

I took a test on the 19th but it came back negative.

What do you guys think?